The invention relates to organic light emitting diode (OLED) devices, and more particularly, to frames integrated with heat dissipation elements for OLED devices.
Among flat panel displays, organic light emitting diode (OLED) displays exhibit characteristics of self-emission, high brightness, wide viewing angle, high response and simple fabrication process, making them popular for the next generation of flat panel displays.
According to driving methods, organic light emitting diode (OLED) displays can be divided into passive matrix light emitting diode (PM-OLED) and active matrix organic light emitting diode (AM-OLED), with the latter more commonly used in flat panel display applications.
Conventionally, it is known that a passive matrix organic light emitting diode (PM-OLED) display is driven to display images by XY matrix electrodes, employing sequential line drive. If the number of scan lines is in the hundreds, the required instantaneous brightness is several hundred times that of the observed brightness. Thus, the instantaneously passed electrical current becomes several hundred times larger and extreme heat is generated resulting in increased operating temperature. Since the deterioration rate of organic light emitting layers is indirect ratio to the operating temperature thereof, however, the luminescent efficiency and lifetime of the OLED device are thereby adversely affected.
One trend in OLED device technology is for higher luminescent efficiency and longer lifetime. As a result, an AM-OLED device with thin film transistors has been provided to solve the aforementioned problems. The AM-OLED device provides panel luminescence with thin and lightweight characteristics, spontaneous luminescence with high luminescent efficiency at low driving voltage, and increased viewing angle, high contrast, high response speed, flexibility, and full color. As the need for larger display devices with higher resolution grows, AM-OLED devices look to become a major trend.
The AM-OLED devices can reduce current through the OLED, thereby controlling overheating. AM-OLED devices, however, typically use thin film transistors (TFTs) as switch devices through which high current passes. Since TFT channels are semiconductor materials such as amorphous silicon or polysilicon, resistance thereof can convert current therethrough to heat, increasing the operating temperature of the OLED device. As the operating temperature, for OLEDs with glass transition temperature (Tg) of about 100° C., increases, the lifetime of the OLED device is reduced. That is, higher operating temperatures cause incremental degradation of the OLED device.
Accordingly, in order to dissipate heat generated by AM-OLED displays, U.S. Pat. No. 6,265,820, the entirety of which is hereby incorporated by reference, discloses a multi-level thermal dissipation structure. Furthermore, U.S. Pat. No. 5,821,692, the entirety of which is hereby incorporated by reference, discloses thermal dissipation fins disposed on the frame to improve dissipation efficiency. Both disclosed OLED displays, however, are restricted by strength and thickness requirements. For example, the multi-level heat dissipation structures can increase total thickness of the OLED devices, and thermal dissipation fins structures may affect the strength of the OLED devices, causing difficulties in assembly.